He claims Special Branch and Lancashire police halted two inquiries into Smith, evidence against him was ignored and no action was taken when child porn was found in his car.

The book also claimed the leader of Rochdale’s Liberal Party, Henry Howarth, tried to bully police into dropping inquiries into the 29-stone monster.

It adds director of public prosecutions Sir Norman Skelhorn refused to prosecute Smith in 1970.

Richard Scorer, a solicitor representing six men who claim to have been molested as boys by Smith, said: “We are examining who knew what about the MP and that includes the Liberal Democrat party and Rochdale Council.”